Illuminating appliance.



0. A. MYGATT.

ILLUMINATING AWUANCE.

APPLgcATloN man nic.31,19|5.

atented Ost.V 22, WM

fifa? www Yo, ai. Y., nssienoa-T @enorm-inn GLASS COMPANY, a

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intrauterine nrrmaarcn.

ieeaearf lowing is a specification.

The Object of my invention is to produce i a compound glass light-transmitting:illuminating appliance for artificial light which will do away with a large'part of the losses in illuminating efficiency due to absorption caused by the incident light raysbeing deviated by refraction back into the incloslure.r

c My invention is especially useful for making compound prism glass lighting appliances where many 0f the rays are directed into downward directions as 1s the case in 1n terior lighting, but it is also useful and efficient for lighting large areas such as streets andv highways. The principle involved is one of paralleling of transmitting prisms.

In the figures, some of the preferred forms have been shown. 'Figure 1 is a vertical plan view partly in cross-section of a globe embodying one form of my invention.

`Fig.`2 is a similar view' of another forrn em bodying my invention. Fig. 3 is a detail of Fig. 1 showing the path of light rays. Fig.

4 is a ver-tical plan viewpartly in cross-section of a shade embodying a furtherform of my invention.

In Fig. 1, the interior shade A is of glass, having a smooth interior J and generally horizontal external prisms C, constructed in the manner hereinafter explained. intervening between this shade and the outer cover is an air-space D; the outer cover B is also of glass 'and has a smooth exterior F, and a generally horizontal prismatic inner surface E calculated as hereinafter set forth. The two shades are fastened together in the manner usual for globes.

In Fig. 2 a similar globe is shown wherein the prisms 1, on the outer cover, are of dif-.- ferent constructlon. f

internal refraction with my appliance. The

prisms and air-space are'greatly4 exaggerated to illustrate more clearly the .pathof the-light rays. Atypical ray 1' from the j lightsource L strikes the inner smooth sur` face J, .ofl the inner shade A, 1s deviated Specification of Letters Patent'.

of al fragmento-f Patented @et 22, 191e.

pplication ld December 31, 1915. Serial No. 69,673.

the glass Wall of the said shade in direction 1^ to one side ,X of the prismatic corrugation'; the ray is then deviated in the direction r2 through the air-passage D,and1 to the outer glass shade and 'impinges onthe face X of one 0f the prisms where it,isv again deviated in the direction r3 taking this course until it leaves the smooth surface F of the outer shade emerging in the direction r4., Except for the presence of the prisms -on the surface of the outer cover either as shown in Figs. 1. 2 or 4, the rays 'after they have left Fig. 1 would go back into the inner cover and be absorbed and lost. The

faces of the horizontal ribs or prisms are Y arranged at angles which will permit a Ina-l liority of the light rays, deviated, to pass through the glass instead of being refracted back from the surface. One of the objec tions to compound globes and reiiectors hitherto is that the rays which pass through compound glass surfaces are refracted back and forth within the glass surface and are largely absorbed and sent out in the undesirable directions. ln the present inventionv the light rays do not strike the faces of the interior prisms within the so-called critical angle so as to be reflected back, but these rays pass through the body of the innershell A and within the air-space t0 the. outer cover reaching that surface at an angle less than 45 degrees and therefore pass through, and out ofthe outer surface.

` Where a higher illumina/ting efficiency from the rays of the inclosed light source` is required, the form used in Fig. 4 is used; the outer surface of the outer cover is covered with horizontal prisms `Hof the form shown, but where it is desirable to clean the device readily, some of the illuminating ef {iciency may be sacriice'd and the outermost and innermost surface ofthe device can be smooth in the manner viown in Fig. l. Where the cleaning is not important and where great diusion is required` the inner surface of -the inner cover' and the outer surface ofthe outer cover of any of the modifications can he `covered with ditusiug ribs'or sandblasted or`acid-etched, as shown in M and N ofFig. 2. 1iWhere modifications of the general shape of Fig. t arc used. a glassand metal thread arrangement G and G is employed. as set vforth in my applica tion filed this' day.

The general contoursv of the two glass inico 

